Hydraulic control system

ABSTRACT

A hydraulic control unit includes a plurality of radial pump units driven by a common drive means. Each of the pump units is provided with an individual control assembly in the form of a control lever for rotating a cam which adjusts the eccentricity of a guide ring coupled to the radial pistons of a pump unit. In this way, the direction and magnitude of flow from the pump is controlled, being fed to or from the pump through a pair of conduits. The conduits are connected to a valve which, in response to the direction of flow in the conduits, is shifted to direct fluid flow in one of two directions through a hydraulic work unit. The valve also serves to direct fluid received from the work unit to a common condenser.

1 United States Patent Inve tor Lester J. Becker $605 Franconia Road,Alexandria. Va.

2230i [21] A pl. No. 858,290 [22] Filed Sept. 16, I969 [45] PatentedAug. 31,1971

[54] HYDRAULIC CONTROL SYSTEM 5 Claims, 12 Drawing Figs.

152 u.s. Cl 60/52 vs, 60/53 R, 60/53 H, 417/426 [5|] lnt.C| ..Fl$b15/18.FlSb 18/00 [50] Field olSearch 60/53 B 53 R, 52 VS; 417/426. 42)

[51%| Relerences Cited UNITED S'I'A'l tas PATFZN'IS 2,414,197 l/l947(iignoux M 60/53 R 2,446,242 ll/lMl-l ()ruhunsky i r i r s 60/53 R 280zen 2,916,879 12/1959 Gondek .v 60/52 3,279,172 10/1966 Kudd et a1.60/53 R Primary Examiner-Edgar W4 Geoghegan AUorrtey-R0berl l. Lainol'ABSTRACT: A hydraulic control unit includes a plurality of radial pumpunits driven by a common drive means. Each of the pump units is providedwith an individual control assembly in the form of a control lever forrotating a cam which adjusts the eccentricity ofa guide ring coupled tothe radial pistons of a pump unit. In this way, the direction andmagnitude-of flow from the pump is controlled, being fed to or from thepump through a pair of conduits The conduits are connected to a valvewhich, in response to the direction of flow in the conduita, is shiftedto direct fluid flow in one of two directions through a hydraulic workunit. The valve also serves to direct fluid received from the work unitton common condenser 28a 28b 28c 28d L m, 525m 5266? seq CONDENSER FIG.1

F IG. 5 F IG. 6

INVENTOII LESTER J. BECKER #ATENTEU M1831 as? 3 501 9 5 sum 2 or 6INVEN'IOI N G LESTER J. BECKER ma/W ATTORNEY PAIENIED A0831 an sum 3 ors LESTER J. BECKER ATTUR N I'IY PATENTED AUEIH I971 3,601,986

sum 5 0r 6 mvsmon LESTER J. BECKER ATTOIIN BY PATENTEDAUG31 I8713.601.986

SHEET 5 [1F 6 206A FIG. 11

I 208 206A 208A mmmm LESTER J. BECKER FIG 12 n} ATTUR N [Y HYDRAULICCONTROL SYSTEM BACKGROUND OF THE INVENTION This invention relates tohydraulic control systems and, more particularly, to hydraulic systemsemploying radial pump units.

It is frequently desirable in hydraulic control systems to provide avariable quantity of fluid under pressure to a hydraulic work unit, suchas a hydraulic cylinder, motor, or the like. To this end, it has beensuggested in the prior art that a variable delivery pump be employed forproviding the variable flow of hydraulic fluid. Radial piston pumps havebeen particularly suitable for this purpose. Such pumps employ a rotorhaving a plurality of radial bores within which pistons are provided inconjunction with guide means for regulating the stroke of the pistons.If the guide means is made eccentric with respect to the axis ofrotation of the rotor, the pistons will be caused to reciprocateradially of the rotor within the bores to effect a pump action. Theextent of eccentricity will regulate the volume of flow provided by thepump.

In prior art hydraulic control systems employing variable delivery pumpsof the radial-piston pump type, it was necessa ry, where a plurality ofhydraulic work units were employed, to provide a plurality of radialpumps with separate drive means for each pump; or, when a single drivemotor was employed, it was necessary to employ elaborate gearing todrive each of the radial pumps separately. It is also difficult in suchprior art systems to control the direction of fluid flow to thehydraulic work unit from the radial pump units. In addition, the meansprovided for adjusting the eccentricity of prior art radial pump unitshave tended to be unduly complex or inconvenient to control.

SUMMARY OF THE INVENTION It is accordingly an object of the presentinvention to provide an improved hydraulic control system employingradial pump units.

More particularly, it is an object of the invention to provide ahydraulic control system employing radial pump units which is versatilein application, simple to control, easy to maintain with a minimuminventory of spare parts, and economical.

It is a further object of the invention to provide a hydraulic controlsystem in which a plurality of radial pump units are driven on a singleshaft and powered by a single prime mover rotating in one direction. Anadditional object relates to the provision, in a system of thischaracter, of control means, capable of remote operation, forindependently controlling the radial pump units for variable output ineither direction. A related object is the provision of a single controlunit for each radial pump unit for controlling the direction of flowfrom the pump unit regardless of the direction of prime mover rotationand the direction of flow from the remaining pump units and for actingas a metering valve for flow control so that flow can be controlled fromzero to full capacity of the pump unit.

Another object is the provision of a control valve in association with aradial pump unit for automatically directing fluid through a hydraulicwork unit for the proper direction as indicated by the control. Arelated object is the provision of a control valve in a system of theaforementioned character which acts as a locking valve to hold acylinder of a hydraulic work unit in any given position.

Briefly, according to the present invention, a single prime mover drivesrotor means including a plurality of radial pump units, each having aplurality of radial bores and a piston in each bore. Each of the radialpump units has individual control means for adjusting the radial strokeof the pistons of each unit so that the direction and magnitude of fluidflow in a pair of conduits leading to and from the radial pump unit iscontrolled independently of the direction and magnitude of flow inconduits associated with the remaining pump units and the direction ofrotation of the rotor means. The system includes special valve meanscoupled to the conduits including a valve body normally biased to amidposition and responsive to fluid flowing from one of the conduits fordirecting fluid through a hydraulic work unit in one direction andresponsive to fluid flowing from the other of the conduits for directingthe fluid through the hydraulic work unit in the opposite direction.More specifically, the special valve includes a valve body or spoolhaving a plurality of valve recesses and a pair of end chambersassociated with springs which bias the valve body and maintain it in amidposition in the absence of fluid flowing from either conduit. Whenfluid is received from either conduit, the pressure thereof is appliedagainst the valve body to shift it and open a fluid path to thehydraulic work unit in the desired direction. In order to control themagnitude and the direction of fluid flow from each of the radial pumpunits, individual control means comprising a control shaft and a cam foradjusting the eccentricity of a guide ring in the pump unit is provided.

The foregoing and other objects, advantages, and features of theinvention and the manner in which the same are accomplished will becomemore readily apparent upon consideration of the following detaileddescription of the invention when taken in conjunction with theaccompanying drawings, which illustrate a preferred and exemplaryembodiment.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic diagram of ahydraulic control system of the invention;

FIG. 2 is a schematic section view of a hydraulic control unit of theinvention generally taken along line 2-2 of FIG. 4 with conduits andcontrol assemblies displaced to aid in the explanation of the invention;

FIG. 3 is a schematic section view taken generally along line 3-3 ofFIG. 2;

FIG. 4 is a schematic section view taken generally along line 4-4 ofFIG. 2',

FIG. 5 is a side view ofa piston of the invention;

FIG. 6 is a front view of the piston of FIG. 5;

FIG. 7 is a view ofa control assembly of the invention;

FIG. 8 is a schematic partial longitudinal section view of the shaft ofthe invention with conduits displaced to aid in the explanation of theinvention;

FIG. 9 is a section view taken generally along line 99 of FIG. 8;

FIG. 10 is a schematic section view ofa valve unit of the invention in afirst position;

FIG. I1 is a schematic section view of the valve unit of FIG. 10 in asecond position; and

FIG. 12 is a schematic section view of the valve unit of FIG. 10 in athird position.

DETAILED DESCRIPTION Referring to FIG. I, it will be seen that ahydraulic control system of the invention comprises a single drive meansor prime mover 20 which drives a single rotor means 22 about a singleshaft 24. A plurality of radial pump units 26a, 26b, 26c, and 26:! areincluded in rotor means 22 and are driven therewith. The direction andmagnitude of fluid flow from each of the pump units is controlled bycorresponding control assemblies 28a, 28b, 28c, and 28d which, as willbe presently explained, individually regulate the pump unitsindependently of the remaining pump units and the direction of rotationof the rotor means. Pairs of conduits 30a and 32a, 30b and 32b, 30c and32c, and 30d connect radial pump units 26a, 26b, 26c and 26d,respectively, with corresponding valve units 34a, 34b, 34c and 34d. Theposition of the control assembly for each pump unit will determinewhether there will be any fluid flow and, if so, the direction of flowin the corresponding conduits. In any case, the corresponding valve willautomatically, in response to the direction of flow in the conduitscontrol the direction of fluid flow to corresponding work units 36a,36b, 36c and 36d through pairs of fluid paths 38a and 40a, 38b and 40b,38c and 400, and 38d and 404, respectively, in a manner to be presentlydescribed.

After fluid is returned from a hydraulic work unit, the fluid will bedirected by the corresponding valve to a condenser 42 through acondenser return conduit 41. The purpose of the condenser is to cool theoil and return it through conduit 43 to an oil storage tank 44. Fluid istaken, in turn, from fluid storage tank 44 through conduits 4S andvalves 34a, 34b, 34c and 34d to the corresponding radial pump unitsthrough one of the corresponding conduits 30a, 30b, 30c and 30d or 32a,32b, 32c and 32d, depending upon the setting of the cor respondingcontrol assembly. Should, however, the control assembly for a particularradial pump unit be in its neutral position, no fluid will flow througheither of the corresponding conduits; and the corresponding valve will,as will be presently explained, serve as a locking valve to maintain thecorresponding hydraulic work unit in the position to which it waspreviously adjusted.

Turning to FIG. 2, it will be seen that a hydraulic control unit of theinvention includes a closed housing 46. The housing includes acylindrical outer wall 48, the ends of which are closed by circular endwalls 50 and 52, being suitably secured thereto by means of bolts 54.End wall 50 has a central exten sion 56 extending outwardly therefromand providing a central bore 58. Likewise, end wall 52 is provided witha central extension 60 extending outwardly in the opposite direction andproviding a central bore 62 of the same internal diameter as bore 58. Itwill be noted that shaft 24 is received in bores 58 and 62 and extendstherebetween. It is to be understood that shaft 24 is relativelystationary with respect to housing 46, and appropriate detent means maybe provided for this purpose. In order to seal the ends of housing 46,an end plate 64 is secured to the end of end wall extension 56 by meansof bolts 66, and an end plate 68 is secured to the end of end wallextension 60 by means of bolts 70. Since it is desirable that the space72 within housing 46 be filled with oil to surround the operating parts.appropriate sealing gaskets 74 and 76 are provided between end wall 50and cylindrical outer wall 48 and between end wall 52 and cylindricalouter wall 48, respective' ly. Similar sealing gaskets (not shown) maybe provided between end plate 64 and end wall extension 56 and betweenend plate 68 and end wall extension 60.

As will be noted from FIGS. 2 and 3, rotor 22 is mounted for rotation onstationary shaft 24 and, for this purpose, includes a central bore 78which is received on shaft 24. Suitable bearing means (not shown) may beprovided between rotor 22 and shaft 24 for facilitating the rotation. Asparticularly shown in FIG. 3, radial pump unit 260 comprises five radialbores 80a extending radially outwardly in substantially the same planefrom central bore 78. From FIG. 2 it will be seen that the remainingradial pump units 26b,26c, and 26d contain substantially identicalradial bores 80b, 80c, and 80d, respectively. Each of the radial boresreceives a piston mounted for reciprocation therein. Referring to FIG.3, for example, it will be seen that radial pump unit 260 comprisespistons 82a within radial bores 804. In like manner, as shown in FIG. 2,pistons 82b, 82c and 82d are received in bores 80b, 80c and 80d,respectively.

As shown in FIGS. and 6, each of the pistons is provided with a pistonextension 84 providing a guide groove 86 defined by an upper lip 88 andinclined surfaces 90 on the upper end of the main portion of the pistonbody. Guide grooves 86 are received on a guide ring 92 which also formsthe inner race of a ball bearing 94, being freely rotatable thereon. Theouter race 96 of the ball bearing is relatively stationary and isreceived within an adjusting ring 98.

The stroke of the pistons is regulated by the degree of cccentricity ofguide ring 92 with respect to the axis of rotation of rotor 22. Whenguide ring 92 is concentric with the axis of rotation of rotor 22, theguide groove 86 of the piston will be equidistant from the axis ofrotation for all points in the rotation of the rotor; and the pistonswill not reciprocate within the bores as the rotor rotates. On the otherhand, if guide ring 92 is shifted to become eccentric of the axis ofrotation, at different points in the rotary travel of rotor 22 thepistons will be shifted relative to the axis of rotation and willtherefore reciprocate within the radial bores. In order to facilitatethe adjustment of the eccentricity of guide ring 92, the adjusting rings98 have adjusting ring extensions I00 provided with adjusting ringextension bores I02 which are dimensioned to receive control cams I04mounted on control shafts I06. As is most clearly shown in FIG. 7, acontrol lever I08 is secured by means of a sleeve on one end of controlshaft 106. Referring to FIG. 2, it will be noted that control shaft 106extends through one of end walls 50 and 52 and is associated with anappropriate sealing gasket 112. The other end of shaft 106 is journaledin a lug 107 projecting from the inner surface of wall 48. As will benoted from FIG. 2, each of radial piston units 26a, 26b, 26c and 26d isprovided with a corresponding control assembly 28a, 28b, 28c and 28dcomprising a guide ring 92, a ball bearing 94, an outer ball bearingrace 96. an adjusting ring 98, and adjusting ring extension I00, anadjusting ring extension bore 102, a control cam I04, a control shaft106. :1 lug 107, a control lever I08, 3 control lever sleeve I10, and acontrol shaft gasket 112. Since all the control levers I08 would notnormally be seen in the view of FIG. 2, some of these have been shown inphantom lines for purposes of illustration. Thus, it will be apparentthat the guide rings of the respective radial pump assemblies may beindividually adjusted independently of the adjustment of the remainingguide rings. Although, as illustrated, control levers I08 are to be actuated manually, it is to be understood that the positions of thecontrol levers may be adjusted automatically by providing ap propriatelinkages to an automatic control system.

In order to limit lateral adjustment of adjusting rings 98 and tomaintain them generally concentric of rotor 22, stops II4 may beprovided mounted on bolts I16 extending through the wall 48 of housing46 on each side of the ring. Since stops I14 extend inwardly of wall 48in close adjacency to adjusting ring 98, they limit the lateral movementthereof, permitting, however, limited adjustment by means of cams I04.Although only a pair of stops 114 are shown in FIG. 3, it is to beunderstood that two such stops are provided for each of the adjustingrings associated with each of the radial pump units.

As already mentioned, rotor 22 is caused to be rotated by a prime moveror motor 20. To this end, as shown most clearly in FIG. 3, a driveshaft118 is driven by prime mover 20 and drives a driving gear I20. Drivegear I20 meshes with a rotor gear 122 (See FIG. 2) forming an integralpart of rotor 22. Due to the unique control assemblies employed with theseveral radial pump units, there is no need to provide directionalcontrol for the prime mover 20 which may drive drive shaft 119continually in one direction and at a constant speed. All adjustments asto magnitude of flow and direction of flow will be accomplished bysuitable adjustment of the corresponding control assembly of aparticular radial pump unit independently of the adjustments of theremaining radial pump units.

The manner in which the hydraulic fluid flows to and from the radialpump units will now be described. As will be seen most particularly inFIGS. 2, 3, 8 and 9, shaft 24 is provided with a plurality of conduitsleading to and from the radial pump units. A first pair of conduits 124and I26 at the lefthand end of shaft 24 are associated with radial pumpunit 260. A second pair of conduits I28 and at the same end of the shaftare associated with radial pump unit 26b. In like manner, at theopposite end of shaft 24 (see FIG. 2) conduits I32 and 134 lead to andfrom radial pump unit 26d, while conduits I36 and 138 are associatedwith radial pump unit 26c. Conduit 124 leads to a port 140 which extendsa substantial distance (nearly halfway) around the circumference ofshaft 24. Similarly, conduit 126 terminates in a port 142 which extendsfor the same distance about the remaining half of the circumferentialperiphery of shaft 24. Ports I40 and 142 are at sub stantially the sameaxial position along shaft 24, thus communicating with the radial bores800 as the rotor rotates thereover. In like manner, conduit I28terminates in port I44 extending about nearly one half of the peripheryof shaft 24 adjacent to the radial bores 80b of radial pump unit 26b,and

conduit 130 terminates in port 146 extending over nearly the remaininghalf of the periphery of shaft 24 adjacent to radial bores 80b. As willbe apparent from FIG. 2, similar ports 148 and 150 are in communicationwith conduits 136 and 138, respectively, and extend about substantialportions of the periphery of shaft 24 adjacent to the radial bores 80cof radial pump unit 26c; and ports I52 and 154 are terminations forconduits 132 and 134, respectively, and communicate with substantialportions of the periphery of shaft 24 adjacent radial ports 80d ofradial pump unit 26 d.

The opposite ends of the conduits in shaft 24 communicate with one ofthe valves 34a, 34b, 34c, and 34d, as will be presently described. Thus,conduit 124 communicates with a port 156 extending through valve housing158 of valve 340, and conduit 126 communicates with a valve port 160extending through valve housing 158. In like manner, conduit 128 leadsto a valve port 162 extending through valve housing 164 of valve 34b,and conduit 130 leads to a valve port [66 extending through this valvehousing. Similar connections are found for conduits 132, 134, 136 and138. Conduit 132 extends to valve port 168 extending through valvehousing 170 of valve 34d while conduit 134 is coupled to valve port 172extending through valve housing 170. Conduit 136 leads to valve port 174extending through valve housing 176 of valve 34c, and conduit 138 leadsto valve port 178 in valve housing 176. The valve housings are suitablysecured to the main housing 46 of the hydraulic control unit by means ofbolts 180.

With particular reference to FIG. 4, it will be seen that valve 344includes a spool 182 positioned within a valve chamber 184 providedinside valve housing 158. lt will be noted that valve spool 182comprises enlarged head portions 186, 188, 190 and 192 engaged with thecylindrical surface of valve chamber 184. Valve spool 182 also includesreduced diameter or neck portion 194 between valve heads 186 and 188,196 between valve heads 188 and 190, and 198 between valve heads 190 and192. These valve neck portions respectively provide valve recesses 200,202, and 204 in valve spool 182. The valve housing 158 is also providedwith a pair of ports 206 and 208 near each end of the valve chamber 184.These valve ports lead to a common conduit 210 which is connected to aport 212 adapted to be coupled by means of a suitable fitting to theline 45 leading from tank 44, whereby hydraulic fluid may be supplied tothe valves from the tank. The valve 340 is also provided with a valveport 214 extending through valve housing 158 to valve chamber 184 at acentral portion therealong. Valve port 214 communicates with a conduit216 leading to a port 218 adapted to be connected by means of a suitablefitting to condenser return conduit 41 (see FIG. 1) leading to fluidcondenser 42. As is evident from FIG. 2, a hole 211 is provided throughend wall 50 from conduit 210 to the space 72 within housing 46 to allowpressure to escape from the system and prevent pressure build up in thehousing which might cause the seals to blow.

Valve 34a is also provided with a valve port 220 extending through valvehousing 158 which is adapted to be connected by means of an appropriatefitting to line 380 leading to or from a hydraulic work unit 360. Nearport 220 is a port 222 leading to a pop valve 224. An additional valveport 226 is provided through valve housing 158 and is adapted to beconnected by means of a suitable fitting to line 400 leading to or fromhydraulic work unit 360. A valve port 228 is located near port 226 andleads to a pop valve 230. Pop valves 224 and 230 are responsive toexcessive hydraulic pressure and are adapted to open a path through aconduit 232 to a valve port 234 communicating with valve recess 202,permitting fluid to be bypassed to condenser 42 through valve port 214and conduit 216.

It is also to be noted that valve spool 182 is provided with apassageway 236 extending from neck 198 and valve recess 204 to theright-hand end of valve head 192. At the other end of valve spool 182 isa similar passage 238 extending from neck 194 and valve recess 200 tothe left-hand end of valve head I86.

Valve chamber 184 includes enlarged end portions forming shoulders 240and 242, and valve blocks 244 and 246 are respectively associated withshoulders 240 and 242 in the enlarged end portions of the chamber. Eachof these valve blocks are biased by means of respective springs 248 and250 into engagement with the corresponding shoulder. The springs bearrespectively against the inner surfaces of end caps 252 and 254 whichinclude threaded sleeves 256 and 258 respectively which engage internalthreads within the valve housing 158. In order to properly position theend caps, they are provided with outwardly extending flanges 260 and262, respectively, which abut against the corresponding ends of thevalve housing 158. Valve block 244 is provided with an aperture 245 inalignment with passage 238, and valve block 246 has an aperture 247 inalignment with passage 236.

The normal position of the valve spool is shown in FIG. 1] with both ofthe valve blocks 244 and 246 biased into contact with the correspondingshoulders 240 and 242. It will be noted that in this position the valveports 206 and 208 appear to be blocked by valve heads 186 and 192.However, in order to permit leak-by of fluid to valve recesses 200 and204 from ports 206 and 208, valve heads 186 and 192 are slightly groovedas indicated at 206A and 208A. The purpose of this arrangement is topermit the pump unit to pick up oil to prime the unit as will becomeapparent when the operation of the hydraulic control systems isdiscussed in detail hereinbelow. The leak-bys also serve to keep thepump unit from building up the pressure in the system, permit instantfluid flow, prevent vacuums in the systems when the pump unit is idling,and prevent creeping of the corresponding work unit.

Each of the valves 34a, 34b, 34c and 34d are substantially identicaland, accordingly, the remaining valves will not be described in detail.It is to be noted, however, that the same reference numerals areemployed for the corresponding parts of the valves where they are seenin the drawings.

The operation of the hydraulic control system of the invention will beapparent from detailed consideration of the opera tion of one of theradial pump units 26a and its associated valve 34a, it being understoodthat the operation of the remaining radial pump units ad valves will besimilar. Let it be assumed, at the outset, that the valve 34a is in itsneutral, or starting position, as shown in FIG. 11. The valve spool 182will a be biased by springs 248 and 250 to its midposition. When thevalve spool is in this position, valve blocks 244 and 246 are biasedinto engagement with corresponding shoulders 240 and 242 and abut thecorresponding ends of the valve spool. Valve head 186 is positioned overvalve port 206, and valve head 192 is positioned over valve port 208.Valve port 220 is closed by valve head 188, and valve port 226 is closedby valve head 190. However, valve ports 156 and are open, communicatingrespectively with valve recesses 200 and 204. In like manner, valve port222 is in communication with valve recess 200, and valve port 228 is incommunication with valve recess 204. The path to condenser 42 throughvalve port 214 and conduit 216 is open from valve recess 202. If, atthis time, the control lever 108 of control assembly 28a correspondingwith radial pump unit 260 is in its neutral position, guide ring 92 willbe concentric with rotor 22 and shaft 24. Under these circumstances,there will be no reciprocation of pump pistons 82a, and no pressure willbe applied by the hydraulic fluid through conduit 124 and valve port 156or through conduit 126 and valve port 160. The valve spool 182 willtherefore remain in its midposition, as shown in H0. 11. Since ports 220and 226 will be closed by valve heads 188 and 190, the valve 344 willserve as a locking valve to hold the cylinder of hydraulic work unit 360in its previously attained position.

If, now, control assembly 28a is adjusted by rotating its lever 108 tobring cam 104 into the position shown in FIG. 3 with respect to radialpump unit 260, the distance A between the lower side of rotor 22 andguide ring 92 will become greater than the distance B between the upperside of rotor 22 and guide ring 92. Guide ring 92 will then be eccentricwith respect to rotor 22, causing reciprocation of pump pistons 82awithin radial bores 80a. 1f it be assumed that rotor 22 is being drivenin the direction of arrow E (see FIG. 3), pistons 820 will begin to drawaway from shaft 24 as they pass end C of rotor center line C-D. Thiswill cause fluid to be drawn into bore 800 from tank 44 through conduit45, port 212, conduit 210, valve port 208, the leak-by provided on head192 of valve spool 182, valve recess 204, valve port 160, conduit 126,and port 142. When a pump bore passes end D of center line C-D, the pumppiston 82a will begin to return toward shaft 24 compressing the fluidwithin the bore and forcing it under pressure out port 140, conduit 124,valve port 156, valve recess 200, through valve passage 238 to the leftend of valve chamber 184. This will cause a pressure buildup on the leftend of spool 182 causing it to be shifted to the right as shown in FIG.10. In this position, spring 250 will be compressed, and spring 248 willbe extended; valve block 244 will abut against shoulder 240 and bespaced from the end of valve head 186', valve block 246 will have beenmoved from shoulder 242 and into abutment with the end of sleeve 258. Asa consequence of this rightward movement, valve port 220 will now be incommuni cation with valve recess 200. Thus, hydraulic fluid underpressure will now flow from valve recess 200 through valve port 220through line 38a to hydraulic work unit 360, from which it will returnvia line 40a to valve port 226. Should the pressure in valve recess 200be excessive, pop valve 224 will open per mitting fluid to flow throughconduit 232 (see FIG. 4) to valve recess 202. As fluid returns from thehydraulic work unit through valve port 226, it is received in valverecess 202 and flows through valve port 214 to conduit 216, from whichit flows out port 218 through line 41 to condenser 42. After thehydraulic fluid is cooled in condenser 42, it is returned to tank 44through line 45.

It is to be noted, that the magnitude of fluid flow is regulated by thelength of the stroke of the pistons 82a of radial pump unit 260. Themagnitude of flow is a function of the degree of eccentricity of guidering 92 with respect to rotor 22 as in dicated by the relativemagnitudes of distances A and B. The flow can be controlled from aslittle as a few drops per minute for precise control of a cylinder inhydraulic work unit 36a up to the full flow permitted by the speed ofrotation of rotor 22 and the capacity of the cylinders of the radialpump unit.

Should it be desired to reverse the direction of flow through hydraulicwork unit 360, it is merely necessary to adjust control assembly 280 toreverse the relative size of distances A and B so that guide ring 92 isrelatively closer to the underside of rotor 22 than to the upper side.In this case, as the radial bores 80a of rotor 22 pass point D of centerline C-D, pistons 824 will draw away from shaft 24 drawing hydraulicfluid into bore 800 from tank 44 through line 45, port 212, conduit 210,port 206, the leak-by permitted by head 186, valve recess 200, valveport 156, conduit 124, and port 140. When the radial bores pass point Cof centerline C-D, the pistons 820 return toward shaft 24 compressingthe hydraulic fluid and forcing it under pressure out port 142, conduit126, valve port 160, valve recess 204, and valve passage 236 to theright-hand end of valve chamber 184. This will cause fluid underpressure to act upon the right-hand end of valve spool 182 causing it tomove leftward until it attains the position shown in FIG. 12. In thisposition, spring 248 will be compressed, and spring 250 will beextended. Valve block 244 will abut against the end of sleeve 256, andvalve block 246 will abut against shoulder 242. The fluid under pressurein valve recess 204 will be caused to flow out valve port 226, whichwill now be open, through line 40a to hydraulic work unit 360 and backfrom hydraulic work unit 360 through line 30a to valve port 220. Shouldthe pressure in valve recess 204 be excessive, pop valve 230 will openand cause the fluid to bypass through con duit 232 (see FIG. 4) to valverecess 202. As fluid is received through valve port 220, it will entervalve recess 202 and be returned through valve port 214, conduit 216,port 218, and line 41 to condenser 42 where it will be cooled beforebeing returned through line 43 to tank 44. As with the other directionof fluid flow through hydraulic work unit 360, the

magnitude of flow will be a function of the relative magnitude ofdistances A and B and may vary from a few drops per minute to the fullflow permitted by the design of the pump.

As will be noted from the foregoing, it is not necessary to reverse thedirection of rotation of rotor 22 in order to reverse the direction offlow through a hydraulic work unit. All that is necessary is suitableadjustment of the control assembly to adjust the eccentricity of guidering 92 with respect to rotor 22 as already described. In point of fact,various pump units of the system may operate oppositely so that some ofthe work units operate in one direction, while others of the work unitsoperate in the opposite direction. Moreover, the flow to some work unitsmay be large, while the flow through other work units may be relativelymuch smaller. A single prime mover rotating in a single direction canthus drive a number of pump units from a single common shaft. Each ofthe pump units will be individually controlled and independent of theother pump units. The direction of flow from one pump unit through ahydraulic work unit may be opposite to the direction of flow from anadjacent pump unit through another hydraulic work unit with the commonshaft driving both pump units still rotating in one direction.

This independent precise flow control and output directional control isa distinct advantage in systems where several motions are desiredsimultaneously. For example, if a forklift truck were equipped with ahydraulic control system of the present invention, a load, such as anaircraft engine, could be precisely positioned. The forklift truck couldbe used for positioning the aircraft engine for assembly or disassemblyfrom an aircraft. The truck could have separate hydraulic work units,each coupled to a separate pump unit of the invention, and thesehydraulic work units could apply up, down, right, left, tilt-up,tilt-down, or rotational motion to the engine for precise alignment ofholes or studs without jogging and with smooth movement because of theclose control of flow (from a few drops per minute to the full capacityof the pump units). A forklift truck provided with a hydraulic controlsystem of the present invention could thus readily adjust for lack ofsurface smoothness and for differing attitudes of the aircraft. Inaddition, individual hydraulic work units could be added to each wheelof the truck to provide a four-wheel drive.

In general, hydraulic control systems of the invention are extremelyversatile and can be used where rugged precise hydraulic systems areemployed or required. For example, there will be considerable utility intanks, gun turrets, and snow removal equipment. On the other hand,hydraulic control systems of the invention can be incorporated inextremely delicate and precise instruments or jigs such as are used inradioactive hot cells for positioning specimens for machining,microscopic studies, and the like. Such fixtures could be remotelycontrolled from outside the hot cell by either mechanical or electriccontrol systems for positioning the control assemblies of the invention.

Although the present invention has been illustrated by an embodimenthaving four radial pump units, it is to be understood that any number ofradial pump units might be employed on a single shaft within the purviewof the present invention. Of course, when the number of radial pumpunits is increased, it will be necessary to increase the capacity of theprime mover, tank, and condenser so that sufficient fluid will beprovided under adequate pressures.

While a preferred embodiment of the invention has been shown anddescribed, it will be readily apparent to those skilled in the art thatchanges can be made without departing from the principles and spirit ofthe invention, the scope of which is defined in the appended claims.Accordingly, the foregoing embodiment is to be considered illustrativerather than restrictive of the invention, and those modifications whichcome within the meaning and range of equivalency of the claims are to beincluded therein.

The invention claimed is:

l. A hydraulic control system comprising: drive means; rotor meansdriven by said drive means and including a plurality of radial pumpunits, each pump unit having a plurality of radial bores and a piston ineach bore; conduit means for conducting fluid to and from said pumpunits; and individual control means for each radial pump unit foradjusting the radial stroke of the pistons of each unit, whereby thedirection and magnitude of fluid flow in said conduit means from each ofsaid pump units is controlled independently of the direction andmagnitude of flow in the remaining pump units and the direction ofrotation of said rotor means, said system further comprising astationary shaft about which said rotor means rotates, said conduitmeans including a first conduit within said shaft communicating with afirst port extending about a first substantial portion of thecircumferential portion of the circumference of said shaft and adaptedto receive fluid from or supply fluid to said radial bores as said borespass thereover and a second conduit within said shaft communicating witha second port extending about a second substantial portion of thecircumference of said shaft and adapted to receive fluid from or supplyfluid to said radial bores as said bores pass thereover, and whereinsaid conduit means comprises valve means for controlling the directionof fluid flow in a pair of fluid lines to and from a hydraulic work unitin response to the direction of fluid flow in said first and secondconduit.

2. A hydraulic control system as recited in claim 1, wherein said valvemeans comprises a valve body having a plurality of valve chambers withina valve casing. spring means for biasing said valve body to amidposition, within said casing, and means communicating fluid underpressure from one of said ports to a corresponding end of said valvebody to shift said valve body toward the other end thereof and establisha fluid path from said one of said ports to a corresponding one of saidfluid lines.

3. A hydraulic control system as recited in claim 2, wherein said valvemeans, when shifted toward said other end, also establishes a fluid pathto a condenser from said other fluid line.

4. A hydraulic control system as recited in claim 2, wherein said valvebody includes four valve heads defining three valve chambers, two ofsaid valve heads closing said fluid lines when said valve body is biasedto said midposition, and said fluid lines communicating with two of saidchambers when said valve body is shifted toward either end.

5. A hydraulic control system as recited in claim 4, wherein said valvefurther comprises a block at each end of said valve casing and saidspring means comprises a spring at each end of the valve casing bearingagainst a corresponding one of said blocks.

1. A hydraulic control system comprising: drive means; rotor meansdriven by said drive means and including a plurality of radial pumpunits, each pump unit having a plurality of radial bores and a piston ineach bore; conduit means for conducting fluid to and from said pumpunits; and individual control means for each radial pump unit foradjusting the radial stroke of the pistons of each unit, whereby thedirection and magnitude of fluid flow in said conduit means from each ofsaid pump units is controlled independently of the direction andmagnitude of flow in the remaining pump units and the direction ofrotation of said rotor means, said system further comprising astationary shaft about which said rotor means rotates, said conduitmeans including a first conduit within said shaft communicating with afirst port extending about a first substantial portion of thecircumferential portion of the circumference of said shaft and adaptedto receive fluid from or supply fluid to said radial bores as said borespass thereover and a second conduit within said shaft communicating witha second port extending about a second substantial portion of thecircumference of said shaft and adapted to receive fluid from or supplyfluid to said radial bores as said bores pass thereover, and whereinsaid conduit means comprises valve means for controlling the directionof fluid flow in a pair of fluid lines to and from a hydraulic work unitin response to the direction of fluid flow in said first and secondconduit.
 2. A hydraulic control system as recited in claim 1, whereinsaid valve means comprises a valve body having a plurality of valvechambers within a valve casing, spring means for biasing said valve bodyto a midposition, within said casing, and means communicating fluidunder pressure from one of said ports to a corresponding end of saidvalve body to shift said valve body toward the other end thereof andestablish a fluid path from said one of said ports to a correspondingone of said fluid lines.
 3. A hydraulic control system as recited inclaim 2, wherein said valve means, when shifted toward said other end,also establishes a fluid path to a condenser from said other fluid line.4. A hydraulic control system as recited in claim 2, wherein said valvebody includes four valve heads defining three valve chambers, two ofsaid valve heads closing said fluid lines when said valve body is biasedto said midposition, and said fluid lines communicating with two of saidchambers when said valve body is shifted toward either end.
 5. Ahydraulic control system as recited in claim 4, wherein said valvefurther comprises a block at each end of said valve casing and saidspring means comprises a spring at each end of the valve casing bearingagainst a corresponding one of said blocks.